A low power 2.4-GHz CMOS direct-conversion transmitter for IEEE 802.15.4

Abstract

A low-power direct-conversion transmitter based on current-mode operation, which satisfies the IEEE 802.15.4 standard, is proposed and implemented in a 0.13-μm CMOS technology. The proposed transmitter consists of DACs, LPFs, variable gain I/Q up-conversion mixer, a divide-by-two circuit with LO buffer, and a drive amplifier. By combining DAC, LPF, and variable gain I/Q up-conversion mixer with a simple current mirror configuration, the transmitter's power consumption is reduced and its linearity is improved The drive amplifier is a cascode amplifier with gain controls and the 2.4-GHz I/Q differential LO signals are generated by a divide-by-two current-mode-logic (CML) circuit with an external 4.8-GHz input signal The implemented transmitter has 30 dB of gain control range, 0 dBm of maximum transmit output power, 33 dBc of local oscillator leakage, and 40 dBc of the transmit third harmonic component. The transmitter dissipates 10.2 mW from a 1.2-V supply and the die area of the transmitter is 1.76 mm × 1.26 mm.